Vector field tomography described in NPL 1 is mentioned as a technique that three-dimensionally analyzes an electromagnetic field structure of a sample from transmission electron photomicrographs. NPL 1 describes that, in order to reconstruct a vector component, that is, three orthogonal components (x, y, z) assigned to individual pixels, a rotation series of images of an observation area at any angle, that is, within a range of −180° to +180°, around the x axis and a rotation series of images of an observation area at any angle, that is, within a range of −180° to +180°, around the y axis, are necessary. The following documents and places of the documents may be mentioned as techniques related to this field.
In PTL 1 (JP 2004-508661 W), there is a description reading: “A sample holder including a sample cradle (12) having a sample grid (14) configured to support a sample (13) to be analyzed; a transfer mechanism (16) that rotates a sample cradle (12) within a sample holder in a plane of the sample (13); a mechanism that inclines a sample cradle (12); and a cryoshutter that, during cryotransfer, protects the sample and can be transferred from a first position at which the sample is protected, to a retracted position are provided (see FIG. 1 and [0012]). There is also a description reading: “A first direction of a sample (13) is determined and a sample cradle (12) is inclined by substantially ±70° to obtain a first set of data. The sample (13) is preferably rotated by 90° on a plane of the sample (13) with a motion transfer mechanism (16) and a second set of inclination data is obtained through substantially ±70.” (see [0015]).
In PTL 2 (JP 2007-188905 A), there is a description reading: “The sample holder 8 is provided with a mechanism in which a holder axis 31 per se connected to the tip of the sample holder 8 is rotated, umbrella gears 32 and 38. The whole tip of the holder 8 can be rotated by 360° around the axis. The umbrella gear 32 is provided at the tip of a sample rotation axis 33. Further, since the umbrella gear 32 and the umbrella gear 38 are in contact with each other so as to engage with each other, the umbrella gear 38 can be rotated by 360° by operating the sample rotation axis 33. A sample base 35 is mounted on a fixed base 39 on the umbrella gear 38. A microsample piece 36 is attached to the tip of the sample base 35.” (see FIG. 7 and [0019]). There is also a description reading: “A holder 8 is inserted into a sample chamber in a transmission electron microscope 1, and electron beams 17 are introduced from a side surface of the sample base 35. That is, electron beams 17 are introduced from a direction perpendicular to a paper surface to observe transmission images. In this case, the umbrella gear 34 can be rotated by moving the sample rotation axis 33 to observe the sample from a direction of 360° around the sample 36.” (see FIG. 5 and [0016]).
In PTL 3 (JP 2001-256912 A), there is a description reading: “A sphere 5, a sample holding rod 6 that is passed into and fixed to the center of the sphere 5, a rotating inner cylinder 3 having a spherical seat for holding the sphere 5, and a rod 4 for inclination that performs inclination of the sphere 5 are provided at the tip of a sample holder 1, and the tip is inserted into an electron lens 11 of an electron microscope. A sample 7 is held on the electron beam 12 side of the sample holding rod 6. An inclined surface of the tip of the rod 4 for inclination is pressed against one end of the sample holding rod 6 to operate the inclination of the Z axis and the Y axis, the rod 4 for inclination is retracted, the inclined surface is rotated in a predetermined inclination direction to again perform pressing to a predetermined inclination angle and thus to change the inclination direction.” (see FIG. 1 and [Solution] in [Abstract]). There is also a description reading: “Two rotation drive mechanisms and one straight advance drive mechanism of a side entry-type sample transfer apparatus including a eucentric-type transfer mechanism are provided on the atmosphere side of the sample holder 1. One of the rotation drive mechanisms is used in 360-degree rotation Θx (theta x) of the X-axis and is connected to the rotating inner cylinder 3. The other rotation drive mechanism and the straight advance drive mechanism are used in inclination operation Θz (theta z) and Θy (theta y) in the Z and Y axes and are connected to the rod 4 for inclination that is placed within the rotating inner cylinder 3.” (see [0013]).
In PTL 4 (JP 8-304243 A), there is a description reading: “A ring 16 and a disk 17 are provided at the tip of a sample fixation rod 11. As indicated by an arrow K in FIG. 5(b), the ring 16 is supported by two points at the tip of the sample fixation rod 11, tiltably around an axis line orthogonal to an axis line of the sample fixation rod 11. As illustrated in the drawing, when an axis line of the sample fixation rod 11 is regarded as X axis, the ring is tiltable to 90 degrees to a plane including X axis. The disk 17 is mounted on the ring 16 through a rotation mechanism and can be rotated by 360 degrees within an end plane of the ring 16.” (see FIG. 5 and [0023]).